Process of modifying the surface of fibrous materials

ABSTRACT

PLASTIC FILM IS DRAWN IN A SINGLE DIRECTION TO ORIENT ITS MOLECULES, AND THEREAFTER FIGRILLATED. PRIOR OT DRAWING, OR SUBSEQUENT TO DRAWING BUT PRIOR TO FIBRILLATION, OR AFTER FIBRILLATION HAS BEGUN, ONE OR BOTH SURFACES OF THE FILM ARE MODIFIED IN A WAY SUCH THAT THE EFFECT OF THE MODIFICATION IS PRESENT IN TEH RESULTING FIBROUS MATERIAL. MODIFICATION MAY BE VACUUM DEPOSITION OF METAL, EMBOSSING. EMBEDDING PARTICLES, PRINTING, OR FLOCKING.

United States Patent 3,636,185 PROCESS OF MODIFYING THE SURFACE OF FIBROUS MATERIALS James Nelson Ruddell, Portadown, and Herbert Alexander Conway Todd, Lisburn, Northern Ireland, assignors to Lambeg Industrial Research Association N0 Drawing. Filed May 3, 1967, Ser. No. 637,317

Int. Cl. B28b 11/04; B29d 7/24 US. Cl. 264-131 3 Claims ABSTRACT OF THE DISCLOSURE Plastic film is drawn in a single direction to orient its molecules, and thereafter fibrillated. Prior to drawing, or subsequent to drawing but prior to fibrillation, or after fibrillation has begun, one or both surfaces of the film are modified in a way such that the effect of the modification is present in the resulting fibrous material. Modification may be vacuum deposition of metal, embossing, embedding particles, printing, or flocking.

This invention concerns fibrous material.

Much work has been carried out, and is presently being carried out, concerning the conversion of material in the form of a film to fibrous form. Broadly the basic concept involves drawing, in one direction, a thin undrawn film of a plastics material, especially polyethylene or polypropylene, in such a way that the film fibrillates, or can readily be fibrillated by subsequent manipulation. The drawing, at the same time. orients the molecules in the direction of drawing so that the fibrillated fibrous material has a strength adequate for textile purposes. The main attraction of such a process, which is hereinafter called a process of the type described, is the possibility of producing textile or like products, especially yarn, directly from film without the involvement of many of the conventional steps used in spinning yarn.

The present invention is based on the appreciation of the fact that by suitably treating the film special effects can be achieved in the end product which otherwise would be expensive, difiicult or perhaps even impossible to ac complish by steps taken at a later stage in the process.

According to the present invention a process of the type described includes the step of modifying the film in such a manner that the effect of the modification is carried through to the resulting fibrous material whereby at least one characteristic thereof is modified.

Preferably the modification consists of a treatment applied to one or both surfaces of the film.

The film may be a single film or it may be composite film consisting of more than one component.

The film can be modified by the inclusion of additives in the material from which the film is made although the film will normally be treated at a later stage but prior to fibrillation. There may however be instances where the film has begun to fibrillate, prior to treatment.

The actual treatment may take diverse forms and a number of them will now be described by way of example only. It is to be understood that these examples are by no means exhaustive.

EXAMPLE 1 A continuous polypropylene film 100 microns thick and six inches Wide has silver applied to both surfaces thereof by vacuum deposition, the thickness of silver being 0.1 micron. The film is then passed through two successive pairs of rollers the speeds of rotation of which are such that the film is drawn in one stage in an atmosphere of steam, the draw ratio being 10:1. The film is then fibrillated in any suitable manner, preferably by subjecting it Patented Jan. 18, 1972 to the action of at least one moving set of pins or needles, the pins or needles moving at the surface of the film in the same direction as the film. The fibrillated film is then simply twisted to form yarn. The yarn has extremely high electrical conductivity which gives improved antistatic properties, and is very lustrous.

EXAMPLE 2 The procedure is the same as in Example 1 except that the fibrillated film, instead of being immediately twisted to make yarn, is converted into staple fibre, the staple length being four inches. The staple fibre is then spun on a modified worsted system to yarn of 30s linen lea, 10 turns per inch and the yarn woven into a fabric suitable for curtain lining. This fabric was found to have good thermal insulated properties.

EXAMPLE 3 A dope-dyed polypropylene film microns thick, six inches wide is first drawn in the same manner as in Examples 1 and 2 and is then passed through an embossing calender with special Schreiner bowls producing of the order of fifty lines per inch both along and across the film. The embossed film is then fibrillated as in the preceding examples, and reduced to six inch staple fibre. The staple fibre is then spun on a modified worsted system to 8s linen lea 3 turns per inch, which yarn is then folded three-ply 2 turns per inch. The resultant three-ply yarn is then tufted into carpet 6 rows per inch 8 tufts per inch. It was found that the carpet had little tendency to show streaks which normally are quite pronounced when using yarn produced from fibrillated film.

EXAMPLE 4 The same polypropylene film as used in the preceding examples is passed between nip rollers and just before entering the nip an even coating of spherical glass particles 10 microns in diameter is applied to the film surfaces and on passage through the nip these become pressed into the film surfaces. The film is then drawn and fibrillated as before and twisted into yarn. This yarn is used to produce fabrics with unusual reflective properties.

EXAMPLE 5 In another embodiment one or both surfaces of a film may be flock printed on an tin-orientated or partly orientated film by electrostatic attraction, prior to fibrillation. The fibrous material produced from such film would have short branch fibres attached thereto, which fibres could have selected characteristics either physical or chemical or both, differing from those of the film material. For instance, 1 mm. nylon fibres of 1 /2 denier per filament, adhered by an adhesive which will not hinder subsequent fibrillation.

It will be appreciated that is not intended to limit the invention to the above examples only, many variations, such as might readily occur to one skilled in the art, being possible without departing from the scope thereof.

We claim:

1. In a process for producing a fibrous assembly from a thin undrawn film of plastics material which comprises the step of drawing in one direction, said film, in such a way that the film fibrillates, or can readily be fibrillated by subsequent manipulation and the molecules of the film are oriented in the direction of drawing so that the fibrillated fibrous material has a strength adequate for textile purposes, the improvement which consists of the additional step of applying only surface modification to the film, the modification being such that the effect of the modification is carried through to the resulting fibrous material whereby at least one characteristic thereof is modified, said additional step being the deposition of metal on said film by a vacuum deposition process.

2. In a process for producting a fibrous assembly from a thin undrawn film of plastics material which comprises the step of drawing in one direction, said film, in such a way that the film fibrillates, or can readily be fibrillated by subsequent manipulation and the molecules of the film are oriented in the direction of drawing so that the fibrillated fibrous material has a strength adequate for textile purposes, the improvement which consists of the additional step of applying only surface modification to the film, the modification being such that the effect of the modification is carried through to the resulting fibrous material whereby at least one characteristic thereof is modified, said additional step being the printing of material on said film.

3. In a process for producing a fibrous assembly from a thin undrawn film of plastics material which comprises the step of drawing in one direction, said film, in such a way that the film fibrillates, or can readily be fibrillated by subsequent manipulation and the molecules of the film are oriented in the direction of drawing so that the fibrillated fibrous material has a strength adequate for textile purposes, the improvement which consists of the additional step of applying only surface modification to '4 the film, the modification being such that the effect of the modification is carried through to the resulting fibrous material whereby at least one characteristic thereof is modified, said additional step being the printing of fiock on said film.

References Cited UNITED STATES PATENTS 2,784,630 3/1957 Koprow et al. 264131 2,948,927 8/1960 Rasmussen 264Fibril. Dig. 2,989,026 6/1961 Gardner et a1 11849 3,137,746 6/1964 Seymour et a1. 264284 3,302,501 2/1967 Greene 264-Fibri1. Dig. 3,374,303 3/1968 Metz 264-284 3,398,441 8/1968 Adachi 281 F FOREIGN PATENTS 211,133 12/1955 Australia 264-146 JULIUS FROME, Primary Examiner H. MINTZ, Assistant Examiner US. Cl. X.R.

264132, 134, 147, 288, Dig. 47; 1177, 12, 107 

